Division of Oncology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan.
Biochem Biophys Res Commun. 2012 Mar 9;419(2):268-73. doi: 10.1016/j.bbrc.2012.02.007. Epub 2012 Feb 10.
The stability of mRNA influences the dynamics of gene expression. The CCR4-NOT complex, the major deadenylase in mammalian cells, shortens the mRNA poly(A) tail and contributes to the destabilization of mRNAs. The CCR4-NOT complex plays pivotal roles in various physiological functions, including cell proliferation, apoptosis, and metabolism. Here, we show that CNOT3, a subunit of the CCR4-NOT complex, is involved in the regulation of the spindle assembly checkpoint, suggesting that the CCR4-NOT complex also plays a part in the regulation of mitosis. CNOT3 depletion increases the population of mitotic-arrested cells and specifically increases the expression of MAD1 mRNA and its protein product that plays a part in the spindle assembly checkpoint. We showed that CNOT3 depletion stabilizes the MAD1 mRNA, and that MAD1 knockdown attenuates the CNOT3 depletion-induced increase of the mitotic index. Basing on these observations, we propose that CNOT3 is involved in the regulation of the spindle assembly checkpoint through its ability to regulate the stability of MAD1 mRNA.
mRNA 的稳定性影响基因表达的动态。CCR4-NOT 复合物是哺乳动物细胞中的主要脱腺苷酸酶，它缩短 mRNA 的 poly(A) 尾巴，有助于 mRNA 的不稳定性。CCR4-NOT 复合物在各种生理功能中发挥关键作用，包括细胞增殖、细胞凋亡和代谢。在这里，我们表明 CCR4-NOT 复合物的一个亚基 CNOT3 参与纺锤体组装检查点的调节，这表明 CCR4-NOT 复合物也参与有丝分裂的调节。CNOT3 耗竭会增加有丝分裂阻滞细胞的数量，并特异性增加 MAD1 mRNA 的表达及其在纺锤体组装检查点中发挥作用的蛋白产物。我们表明 CNOT3 耗竭稳定 MAD1 mRNA，并且 MAD1 敲低会减弱 CNOT3 耗竭诱导的有丝分裂指数增加。基于这些观察结果，我们提出 CNOT3 通过调节 MAD1 mRNA 的稳定性参与纺锤体组装检查点的调节。
